## 41Axx Approximations and expansions

- 41A05 Interpolation [See also 42A15 and 65D05] (1)
- 41A10 Approximation by polynomials (For approximation by trigonometric polynomials, see 42A10) (1)
- 41A15 Spline approximation (5)
- 41A17 Inequalities in approximation (Bernstein, Jackson, Nikol`skiï-type inequalities)
- 41A20 Approximation by rational functions
- 41A21 Padé approximation
- 41A25 Rate of convergence, degree of approximation
- 41A27 Inverse theorems
- 41A28 Simultaneous approximation
- 41A29 Approximation with constraints
- 41A30 Approximation by other special function classes (3)
- 41A35 Approximation by operators (in particular, by integral operators) (3)
- 41A36 Approximation by positive operators
- 41A40 Saturation
- 41A44 Best constants
- 41A45 Approximation by arbitrary linear expressions
- 41A46 Approximation by arbitrary nonlinear expressions; widths and entropy
- 41A50 Best approximation, Chebyshev systems
- 41A52 Uniqueness of best approximation (1)
- 41A55 Approximate quadratures (1)
- 41A58 Series expansions (e.g. Taylor, Lidstone series, but not Fourier series) (3)
- 41A60 Asymptotic approximations, asymptotic expansions (steepest descent, etc.) [See also 30E15] (1)
- 41A63 Multidimensional problems (should also be assigned at least one other classification number in this section) (1)
- 41A65 Abstract approximation theory (approximation in normed linear spaces and other abstract spaces)
- 41A80 Remainders in approximation formulas
- 41A99 None of the above, but in this section